The most obvious reason for Quirrel’s actions at the end of this chapter is to prevent the prophecy from coming true. The next most obvious, and what I think is correct, is that he’s taking those precautions because he wants to make sure Harry doesn’t die before he makes the prophecy come true.
Professor Quirrell spoke with eyes half-lidded, looking out like through slits. “More than the question of whom the prophecy spoke—who was meant to hear it? It is said that fates are spoken to those with the power to cause them or avert them.
The most obvious reason for Quirrel’s actions at the end of this chapter is to prevent the prophecy from coming true. The next most obvious, and what I think is correct, is that he’s taking those precautions because he wants to make sure Harry doesn’t die before he makes the prophecy come true.
http://hpmor.com/chapter/86
Quirrell is of the view that prophecies are sometimes of things that can be prevented.
But a prophecy can’t be prevented from coming true. Otherwise it would just be a prediction.
But how it comes true is very flexible, and we are warned repeatedly against any simple naive notion like ‘a prophecy will come true literally as you think it will’, in http://hpmor.com/chapter/86 http://hpmor.com/chapter/28 http://hpmor.com/chapter/72 (especially chapter 86 - why would Merlin bother with a Hall if it was as futile as all that?).
It’s worth noting that Harry’s prophecy is partially imperative and partially conditional.